Bifenthrin recovery from glue-line-treated plywood
J Norton, L Stephens
Plywood and laminated veneer lumber (LVL) can be protected from termite damage by addition of bifenthrin to the adhesive used in product manufacture. However, conditions associated with this manufacturing process may lead to deterioration or immobilisation of the active ingredient. In order to determine compliance with treatment specifications, it is important that the concentration of a preservative in the manufactured product can be accurately determined. Plywood test panels were prepared from hoop pine (Araucaria cunninghamii) veneers, using four types of adhesive; isocyanate, high alkali phenol formaldehyde (PF), low alkali PF and urea formaldehyde (UF). Bifenthrin was added to each adhesive mix to achieve three concentrations of the active ingredient in the final product. After manufacture, the concentrations of bifenthrin were determined using two sampling techniques. The concentration of bifenthrin recovered from the treated product varied with the type of adhesive used. The implications for compliance monitoring are discussed.